Influence of metacarpophalangeal joint position on basal joint-loading in the thumb

Distribution of strength potential of the thumb muscles and their relationship to trapeziometacarpal osteoarthritis: An exploratory cadaveric study

BACKGROUND

The ten muscles of the thumb allow for a variety of movement combinations yielding similar functional outcomes yet using different load transmission with different biomechanical stresses resulting in heterogenous trapeziometacarpal wear patterns. Our exploratory study investigates the correlation between the severity and location of trapeziometacarpal joint osteoarthritis and estimated individual thumb muscles maximal force.

METHOD

Normalized muscle mass to body mass and physiological cross-sectional area ratio were calculated following systematic muscular dissection of 19 cadaveric hands, 60 % males, average age 79.2, SD = 7.1. Correlations were analyzed with 3 different measures of articular degenerations.

FINDINGS

Moderate negative correlation was found between Eaton-Glickel osteoarthritis grade and normalized muscle mass of opponens pollicis (rₛ = -0.59, p < .01) and abductor pollicis longus (rₛ = -0.60, p < .01). Moderate negative correlation was also found between trapeziometacarpal index and normalized opponens pollicis and abductor pollicis longus muscle mass (rₛ = -0.63, p < .01) and (rₛ = -0.51, p < .05), respectively. No correlation was identified between physiological cross-sectional area ratios and the above degeneration metrics.

INTERPRETATION

Our current findings identified moderate negative correlations between the normalized mass to body mass of abductor pollicis longus and opponens pollicis for both Eaton-Glickel osteoarthritis grade and trapeziometacarpal index, which would support the current hand therapy exercise recommendations for the arthritic trapeziometacarpal population. Caution must be taken in the interpretation of correlations with articular zones degradation as our analytical power was reduced by the complete eburnation of few articular surfaces.

The Use of Stromal Vascular Fraction, Platelet-rich Plasma, and Stem Cells in the Treatment of Thumb Carpometacarpal Osteoarthritis

Background

Thumb function is integral to hand movement and overall hand function. Impairment, often caused by carpometacarpal (CMC) arthritis, reduces the quality of life. Here, we explored a novel approach using a mixture of the stromal vascular fraction, adipose-derived stem cells, and platelet-rich plasma to treat symptomatic trapeziometacarpal osteoarthritis.

Methods

Retrospective data from 30 hands of 19 patients classified as Eaton and Littler stages 1-4 were analyzed. Platelet-rich plasma and fat were collected under sterile conditions, followed by centrifugation, stem cell extraction, and injection of the mixture into the thumb CMC joint under x-ray guidance. The measurement parameters included the visual analog scale pain score, grip strength, pinch strength, and Thumb Disability Examination (TDX) score. Statistical analysis was performed using paired t tests to evaluate the outcomes across the entire group, individual stages, and early/late stages.

Results

We examined 30 hands of 19 patients with trapeziometacarpal osteoarthritis. Pain reduction was significant at 6 and 24 months for all stages, particularly stages 2 and 3. Substantial pain reduction was also observed at the early and late stages. The TDX score decreased significantly in all groups after 6 and 24 months. Hand function notably improved with significant gains in tip-to-tip pinch strength at 24 months and palmar pinch strength at 6 and 24 months. No complications were observed.

Conclusions

The intra-articular injection of autologous conditioned plasma/stromal vascular fraction in patients with thumb CMC arthritis, in all stages, helps to improve pain symptoms and postpone potential resection arthroplasty with minimal surgical intervention and risks.

Extracorporeal Shock Wave Therapy (ESWT) vs. Exercise in Thumb Osteoarthritis (SWEX-TO): Prospective Clinical Trial at 6 Months

Rhizarthrosis is the most frequent form of osteoarthritis and is responsible for pain, disability and reduced functionality. The aim of the study is to investigate the clinical effects of shock wave treatment in patients suffering from arthritis of the first finger. A prospective clinical study was designed, in which 72 patients affected by rhizarthrosis were randomized to treatment with shock waves or exercises; in both groups an immobilization brace was used on the first finger. At recruitment and at 1, 3 and 6 months, patients received assessments of pain (VAS), functionality (FIHOA) and disability (DASH); furthermore, the perception of improvement was monitored during follow-ups (Roles and Maudsley Score). In both groups there was a significant improvement in all scores in the comparison between recruitment and 6 months. The perception of improvement was statistically better in the shock wave group than in the exercise group at 1, 3 and 6 months. The regression analysis showed that the reduction of VAS and DASH were statistically influenced by shock wave treatment (p < 0.001). Both therapies are effective in managing patients suffering from arthritis of the first finger, but the shock wave treatment could ensure greater persistence of improvements.

Intraoperative cartilage analysis of the first carpometacarpal joint - comparison with conventional staging according to Eaton and Littler

INTRODUCTION

Osteoarthritis of the first carpometacarpal joint is a common pathology of the hand, which may show an increasing prevalence in Germany due to the demographic development. In recent years, not only the current gold standard - the resection arthroplasty of the thumb saddle joint - has been used, but also therapeutic thumb saddle joint arthroscopy. In addition to the patient's clinical complaints, radiographic diagnostics have been used to decide on treatment, although it has not been proven whether there is a correlation between imaging and clinical complaints.

MATERIALS AND METHODS

Between 2020 and 2022, 20 articular surfaces of the thumb saddle joint undergoing resection arthroplasty for symptomatic basal thumb osteoarthritis were prospectively examined, mapped and compared with preoperative conventional radiographs.

RESULTS

The evaluation of the corresponding articular surfaces showed a higher cartilage destruction at the articular surfaces of the trapezium compared to the first metacarpal. No correlation was found between the stage of osteoarthritis and the Eaton-Littler classification.

CONCLUSIONS

Overall, there is a patient-specific heterogeneity of the cartilage damage of the articular surface of the trapezium bone, as well in the metacarpal bone I base in relation to the radiographic diagnosis. Furthermore, an inhomogeneity of the radiographic stage of osteoarthritis of the carpometacarpal joint according to Eaton and Littler in relation to the intraoperatively assessed cartilage damage. The statistical significance of the surgically assessed cartilage damage in relation to the conventional radiographs could not be demonstrated. Thus, the treatment of symptomatic osteoarthritis of the carpometacarpal joint should primarily address the patient's individual complaints. The radiographic classification according to Eaton and Littler can be used as an additional factor to decide on the surgical procedure but should not delay the therapeutic treatment.

LEVEL OF EVIDENCE

III.

Using active or functional range of motion as a further indicator to detect hand osteoarthritis. A preliminary study

PURPOSE

Propose further indicators for helping to detect hand osteoarthritis (HOA) using either active or functional ranges of motion (AROM or FROM).

METHOD

Hand kinematics data of 16 hand joint angles from previous studies were used, taken from healthy participants and HOA patients with differently affected joints and distinct levels of compromise. Data consisted of: (i) AROM (extreme values and ranges); (ii) FROM while performing the Sollerman Hand Function Test (mean, extreme percentiles and ranges). Two linear discriminant analyses (stepwise method) were conducted, one per dataset (AROM and FROM), with condition (healthy/patient) as the grouping variable. The potential predictors were the data from the joints with significant differences between samples for each analysis (A-predictors and F-predictors).

RESULTS

Good sensitivity-specificity values of 85.2-90.9% and 93.8-93.9% for F-predictors and A-predictors, respectively. Sets of predictors corresponded to the joints more commonly affected by HOA. F-predictors: lower maximal flexion of carpometacarpal and interphalangeal thumb joints, higher maximal flexion of thumb metacarpal joint, lower flexion/extension range of ring proximal interphalangeal joint and higher maximal little finger adduction. A-predictors: narrower flexion/extension range of the thumb carpometacarpal joint, lesser extension of the ring metacarpophalangeal joint; lower flexion of the middle finger proximal interphalangeal joint along with a narrower palmar arch range.

CONCLUSION

Both sets of predictors provide discrimination capacity of HOA with good sensitivity-specificity, slightly better for A-predictors. The AROM measurement is technically less demanding and can be clinically applied even with manual goniometry.

Rhizarthrosis Part II: A New Approach of Manual Therapy and Therapeutic Exercise

Rhizarthrosis (RA), also known as trapezium-metacarpal osteoarthritis, is a degenerative condition affecting the thumb's first joint, leading to functional impairment and pain. Conservative treatment options are preferred for mild to moderate cases (Eaton-Littler grades I and II) and typically encompass a range of therapeutic modalities, including manual therapy. However, for the existing manual therapy techniques, there is a lack of comparative studies for efficacy, and therapeutic exercises are often generic and non-specific to RA. This study proposes a novel treatment protocol that combines manual therapy with specific therapeutic exercises grounded in the biomechanical analysis of the trapeziometacarpal joint. The focus is on enhancing joint stability, reducing pain, and improving function. The manual therapy component includes three phases. A passive phase, during which joint distractions are applied to alleviate discomfort and improve joint mobility. An active phase that addresses joint mobility on the adduction-abduction plane, the first plane of movement to suffer limitation: the therapist facilitates the isometric adduction of the thumb, followed by an assisted abduction. A second active phase is where Mulligan's Mobilization With Movement concept is applied. This technique involves passive pain-free joint mobilization with simultaneous active finger movements, to provide additional therapeutic benefits. The therapeutic exercises component focuses on strengthening the first dorsal interosseous muscle as an abductor to reduce thumb adductor muscle activation and joint stress. Patients are encouraged to perform finger spreading exercises using a rubber band between the first and fifth fingers, emphasizing first dorsal interosseous activation and stability of the thumb. This type of muscle strengthening does not involve movement of the trapeziometacarpal joint. It is recommended to start performing 5-10 repetitions or 5 seconds of isometric contraction, repeat throughout the day, and progressively increase the load by adding a turn to the rubber band or changing it, increasing the number of repetitions bringing it to 15 and/or increase the isometric contraction time to 10/15 seconds. The proposed therapeutic rationale, informed by biomechanical insights, lays a promising foundation for further investigation. Nevertheless, empirical validation through rigorous clinical trials remains essential to substantiate its clinical utility and advance the management of RA.

In-vivo kinematics of the trapeziometacarpal joint in dynamic pinch motion using four-dimensional computed tomography imaging

OBJECTIVE

CT imaging precisely and quantitatively analyzes the kinematics of the carpal bones to evaluate the etiology of related osteoarthritis. Previous studies have investigated the kinematics of the trapeziometacarpal joint using static CT scans of various postures including the pinch position. This study analyzed the in-vivo kinematics of the trapeziometacarpal joint during dynamic pinch motion in young healthy volunteers using four-dimensional CT.

MATERIALS AND METHODS

Twelve healthy young volunteers participated in this study. Each participant held the pinch meter between their thumb and index finger and pinched it with maximum force for a period of 6 s. This series of movement was recorded using a four-dimensional CT. The surface data of the trapezium and first metacarpal of all frames were reconstructed, and bone movement at the trapeziometacarpal joint was calculated using sequential three-dimensional registration. The instantaneous pinch force of each frame was measured using a pointer on a pinch meter that was reconstructed from the CT data.

RESULTS

The first metacarpal was abducted (15.9 ± 8.3°) and flexed (12.2 ± 7.1°) relative to the trapezium, and significantly translated to the volar　(0.8 ± 0.6 mm) and ulnar directions (0.9 ± 0.8 mm) with maximum pinch force. This movement consistently increased with the pinch force.

CONCLUSION

This study successfully employed 4D-CT to precisely demonstrate changes in rotation and translation at the trapeziometacarpal joint during pinch motion for various instantaneous forces.

Rhizarthrosis Part I: A Literature Review

Rhizarthrosis (RA), or trapeziometacarpal osteoarthritis, is an arthritic degenerative process that affects the first joint of the thumb. The objective of this work is to provide therapists with an overview of the fundamental issues related to the therapeutic management of trapeziometacarpal joint instability. Prevalent in females, especially post-menopause, and linked to age, RA involves ligament and muscle structures, with causes ranging from hormonal influences to mechanical factors. Understanding the biomechanics, stability, and factors contributing to RA is crucial for effective intervention. This study explores the role of ligaments, muscles, and anatomical variants in thumb joint degeneration, emphasizing the importance of stability and congruence. RA manifests as pain at the base of the thumb, limiting grip strength and hindering everyday tasks. Pain initially occurs during specific movements but can progress to constant discomfort, affecting sleep. Chronic RA leads to joint stiffness, deformities like the "Z thumb," and muscle atrophy, impacting daily functions. Clinical evaluation involves pain assessment, joint mobility examination, and palpation. Diagnostic tests like the grind test and lever test aid in confirming RA. Radiographic examination reveals joint space degeneration and osteophytes and helps classify RA stages using the Eaton-Littler classification. Conservative treatment aims to alleviate pain, reduce joint stress, and enhance function. Orthoses help stabilize the joint. Therapeutic exercises, emphasizing muscle strength and dynamic stability, prove beneficial. Manual therapies like neurodynamic, Kaltenborn, Mulligan, and Maitland techniques target pain reduction and improve joint mechanics. The studies on conservative approaches provide evidence that a multimodal intervention consisting of joint mobilization, neural mobilization, and exercise is beneficial in reducing pain in patients with RA. When conservative therapy fails, surgical intervention is indicated.

Assessment and treatment of nonsurgical thumb carpometacarpal joint osteoarthritis: A modified Delphi-based consensus paper of the American Society of Hand Therapists

BACKGROUND

While the literature is abundant on hand therapy assessment and treatment of nonsurgical thumb carpometacarpal (CMC) osteoarthritis (OA), clarity and uniformity are meager, making it a desirable diagnosis to establish expert consensus.

PURPOSE

This study aimed to ascertain if consensus exists for the assessment and treatment of nonsurgical management of thumb CMC OA in the hand therapy clinical setting.

STUDY DESIGN

This was a consensus paper via the modified Delphi approach.

METHODS

A modified Delphi method was used to determine consensus among an expert panel, including hand therapists and hand surgeons, via two online surveys. A consensus paper steering committee (from the American Society of Hand Therapist's research division) designed the surveys and analyzed responses. Consensus was established as 75% agreement among the expert panel. Demographic information was collected from the expert panel.

RESULTS

The expert panel included 34 hand therapists and seven hand surgeons. The survey response rates were 93.6% for the first survey and 90.2% for the second survey. Consensus recommendations were classified according to the World Health Organization categorization. These included evaluating the body structures for clinical signs/clinical testing and body functions for pain, range of motion for palmar abduction, radial abduction, opposition, and thumb metacarpal phalangeal flexion/extension, and grip and tripod pinch strength. Further consensus recommendations were for the assessment of function using a region-specific, upper extremity patient-reported outcome measure (activity and participation), environmental factors, outcome expectation, and illness perception within the patient's unique environmental and social contexts. Treatment recommendations included the use of an orthosis during painful activities, a dynamic stability program (stable C posture, release of tight adductors, and strengthening of stabilizers), patient education, joint protection techniques, adaptive equipment, and functional-based intervention.

CONCLUSIONS

The findings describe the consensus of a group of experts and provide a clinical reference tool on the hand therapy assessment and treatment of nonsurgical thumb CMC joint OA.

Effect of a stabilization exercise program versus standard treatment for thumb carpometacarpal osteoarthritis: A randomized trial

STUDY DESIGN

Randomized, interventional trial with 1 year follow-up.

INTRODUCTION

Though recommended, evidence is lacking to support specific exercises to stabilize and strengthen the first carpometacarpal (CMC) joint for cases of osteoarthritis (OA).

PURPOSE OF THE STUDY

To determine in a naturalistic setting, whether standard treatment plus a home exercise program (ST+HEP) is more effective than standard treatment (ST) alone in improving Quick Disabilities of Arm, Shoulder and Hand (qDASH) scores, and secondarily, in other patient-centered (pain, function) and clinical outcomes (range of motion, strength).

METHODS

A total of 190 patients from a hand therapy practice in northwestern PA were enrolled by informed consent and randomized into ST or ST+HEP groups. Average age was 60 years, most were female (78%) with sedentary occupations most common (36%). ST group received orthotic interventions, modalities, joint protection education and adaptive equipment recommendations, while the ST+HEP group received a home exercise program in addition to ST for 6-12 months. Follow-up occurred at 3, 6, and 12 months. Outcomes included grip strength, pinch strength, range of motion (ROM), qDASH, Patient Specific Functional Scale (PSFS) and pain ratings. At the 6 month mark, all subjects could change groups if desired. Efficacy data analysis included both parametric and non-parametric tests. The threshold for statistical significance was 0.05 and adjusted for multiple comparisons.

RESULTS

Repeated measures ANOVA failed to show a statistically significant difference in strength and ROM assessments between treatment groups over the 12 month follow-up (P ≥ .398). Differences between groups did not exceed 13%. Both the ST and ST+HEP groups evidenced improvement over time in most patient-focused assessments (P ≤ .011), including improvements exceeding reported clinically important differences in pain with activity and PSFS scores. Scores for these measures were similar at each follow-up period (P ≥ .080) in each group. The presence of CTS exerted no effect on outcomes; longer treatment time was weakly related to poorer qDASH and PSFS scores initially. Of those enrolled, 48% of subjects completed the study.

CONCLUSIONS

The addition of a high-frequency home exercise program did not improve clinical or patient-centered outcomes more so than standard care in our sample however, study limitations are numerous. Both groups had decreased pain with activity and improved PSFS scores, meeting the established minimally clinically important difference (MCID) of each at 6 and 12 months. Adherence with the home program was poor and/or unknown.

Metacarpophalangeal hyperextension in thumb basal joint osteoarthritis: Radiological study and implications for treatment

We report a series of 95 consecutive patients operated on for total trapeziometacarpal joint replacement, screening for radiological characteristics to differentiating patients with and without preoperative MCP hyperextension. Loss of thumb column length and metacarpal head circularity on lateral view were quantified. Statistically, a combination of reduced length and circular metacarpal head was a determining factor for MCP hyperextension. We therefore believe it is essential to restore thumb column length in surgery for trapeziometacarpal osteoarthritis and to avoid trapeziectomy in patients with a circular head on lateral view. LEVEL OF EVIDENCE: III; prospective cohort study.

Autologous Fat and Platelet-Rich Plasma Injections in Trapeziometacarpal Osteoarthritis: A Systematic Review and Meta-Analysis

BACKGROUND

For the treatment of carpometacarpal arthritis of the thumb, various therapies are used. Infiltration therapy with autologous substances such as platelet-rich plasma and autologous fat have recently gained increasing attention because of beneficial pain-reducing effects in arthritis and the associated regenerative potential. However, the extent of clinical evidence in this area and how well autologous substances work in terms of pain reduction and improvements in hand function remain unclear.

METHODS

A systematic review and meta-analysis were conducted to evaluate the current evidence and to provide more insight into pain reduction and improvement in hand function after infiltration of autologous substances. The authors identified 11 clinical trials, of which we included eight in the meta-analysis.

RESULTS

Autologous substances achieved a good and long-lasting pain reduction, which may also be accompanied by corresponding improvement in hand function. Autologous substances appear to be more effective than corticoid infiltrations. The infiltration of autologous fat seems to be particularly promising in more advanced stages of carpometacarpal arthritis of the thumb. Our meta-analysis showed a mean pain reduction of 2.4 to 3 in visual analogue scale score and a reduction of 18 to 19 points in the Disabilities of the Arm, Shoulder, and Hand questionnaire after infiltration with autologous substances.

CONCLUSION

Both platelet-rich plasma and autologous fat infiltration offer an efficient and long-lasting, minimally invasive therapy option in the treatment of carpometacarpal arthritis of the thumb.

The biomechanics of osteoarthritis in the hand: Implications and prospects for hand therapy

BACKGROUND

The unique anatomy of the human hand makes it possible to carefully manipulate tools, powerfully grasp objects, and even throw items with precision. These apparent contradictory functions of the hand, high mobility for manual dexterity vs high stability during forceful grasping, imply that daily activities impose a high strain on a relatively instable joint. This makes the hand susceptible to joint disorders such as osteoarthritis. Both systemic (eg, genetics, hormones) and mechanical factors (eg, joint loading) are important in the development of osteoarthritis, but the precise pathomechanism remains largely unknown. This paper focuses on the biomechanical factors in the disease process and how hand therapists can use this knowledge to improve treatment and research.

CONCLUSION

Multiple factors are involved in the onset and development of osteoarthritis in the hand. Comprehension of the biomechanics helps clinicians establish best practices for orthotics intervention, exercise, and joint protection programs even in de absence of clear evidence-based guidelines. The effect and reach of hand therapy for OA patients can be expanded substantially when intervention parameters are optimized and barriers to early referrals, access reimbursement, and adherence are addressed. Close and early collaboration between hand therapists and primary care, women's health, rheumatology, and hand surgery providers upon diagnosis, and with hand surgeons pre and postoperatively, combined with advances in the supporting science and strategies to enhance adherence, appear to be a promising way forward.

Management of the Metacarpophalangeal and Scaphotrapeziotrapezoidal Joints in Patients with Thumb Trapeziometacarpal Arthrosis

Basilar thumb osteoarthritis at the trapeziometacarpal joint is the second most common location of osteoarthritis in the hand. Arthritis and instability of the thumb MCP joint can be quite debilitating, given the crucial role the joint plays in thumb dexterity. Advanced basilar thumb osteoarthritis often leads to collapse of the first ray with compensatory hyperextension of the thumb metacarpophalangeal (MCP) joint and is accompanied by arthritis in the scaphotrapezialtrapezoid joint. Here the authors discuss the management of MCP hyperextension and scaphotrapezoidal osteoarthritis in the setting of basilar thumb osteoarthritis.

Carpometacarpal and metacarpophalangeal joint collapse is associated with increased pain but not functional impairment in persons with thumb carpometacarpal osteoarthritis

INTRODUCTION

Due to the complex shape of the carpometacarpal (CMC) joint, a fixed joint collapse deformity of the thumb CMC (CMC1) and metacarpophalangeal (MCP1) joint can present in advanced stages of CMC1 osteoarthritis (OA), resulting in adduction of the first metacarpal (MC1) and hyperextension of the MCP1.

PURPOSE OF THE STUDY

To determine whether joint collapse deformity is associated with worse pain and/or functional impairment.

STUDY DESIGN

Cross-sectional.

METHODS

This study used the baseline data from 140 patients enrolled in a longitudinal study of treatment for CMC1 OA. (efficacy of combined conservative therapies on clinical outcomes in patients with CMC1 OA). Joint collapse was determined at baseline using a pinch gauge. Pain was assessed on a visual analog scale (0-100) and function was assessed using the Functional Index for Hand Osteoarthritis questionnaire (0-30). Pain and function and the presence of joint collapse were entered in a univariate logistic regression. The final adjusted model for pain and joint collapse included age and sex. The final adjusted model for function and joint collapse included Kellgren Lawrence grade and grip strength.

RESULTS

About 20% of participants demonstrated joint collapse on the tip-pinch test. The presence of joint collapse was associated with increased pain in the unadjusted [P = .047, OR = 2.45, 95% CI (1.01, 5.910)] and adjusted model [P = .049, OR = 2.45, 95% CI (1.00, 5.98)].

CONCLUSION

CMC1 patients with joint collapse reported increased pain compared with those without joint collapse. Future studies should determine the relationship between thumb hypermobility and joint collapse and how to manage these conditions effectively.

[Conservative treatment options for symptomatic thumb trapeziometacarpal joint osteoarthritis]

BACKGROUND

There are numerous non-surgical treatment options for basal thumb osteoarthritis (OA).

OBJECTIVES

Aetiology, clinical appearance and diagnosis of basal thumb OA, explanation of the individual non-surgical treatment options, presentation of the current state of studies.

MATERIAL AND METHODS

Search for case analyses, studies, systematic reviews and meta-analyses using PubMed and LIVIVO.

RESULTS

Intraarticular injections have no more than short-term success with the risk of infection, which should not be underestimated. Radiotherapy seems to be an effective treatment, but little research has been done on this. Physiotherapy and splinting treatment promise long-term improvement of clinical symptoms and hand function.

CONCLUSION

Basal thumb OA is a common and serious condition, which in the case of continuous pain should be diagnosed and treated adequately. A multi-modal therapeutic regimen with avoidance of repetitive intra-articular injections seems to provide the best long-term results.

Thumb Carpometacarpal Instability

The basal joint complex of the thumb provides the framework necessary for function of the human hand. Although its unique saddle articulation allows for a wide range of motion necessary for routine function of the hand, it is rendered inherently unstable because of poor bony congruency and reliance on its capsuloligamentous support. Painful instability of this joint can stem from several causes including traumatic dislocation, various hypermobility conditions, and chronic overuse and microtrauma. A thorough history and examination as well adequate imaging is necessary for proper evaluation of instability. Treatment options range from nonoperative modalities to surgery, which entails closed, percutaneous, or open reduction with numerous ligament repair and reconstruction techniques. Arthroscopy can also serve to be a useful adjunct for assessment of the joint and stabilization of the critical capsuloligamentous structures. This review outlines the critical osseous and soft-tissue anatomy surrounding the thumb carpometacarpal joint, the key points in evaluating patients presenting with acute traumatic and chronic thumb carpometacarpal instability without fracture or arthritis, and reviews both nonoperative and operative treatments of this injury.

Anatomy and biomechanics of healthy and arthritic trapeziometacarpal joints

Understanding the biomechanics of the trapeziometacarpal (TMC) or first carpometacarpal (CMC1) joint, the pathophysiology of basal thumb arthritis, the design and performance of surgical procedures require a solid anatomical basis. This review of literature summarizes the most recent data on the descriptive, functional, and comparative anatomy of healthy and arthritic TMC joints.

Metacarpophalangeal joint instability in trapeziometacarpal osteoarthritis: A systematic review

Thumb metacarpophalangeal instability is commonly found in conjunction with trapeziometacarpal osteoarthritis. If not corrected, it can have detrimental effects on the outcome. The authors describe the two types of metacarpophalangeal deformities - hyperextension and valgus - their pathophysiology and the surgical repair techniques available to surgeons. An algorithm for treating this instability is presented.

Thumb Metacarpophalangeal Joint Arthritis

Arthritis of the thumb metacarpophalangeal joint can be debilitating whether in isolation or in conjunction with degenerative disease at the adjacent joints. Despite its crucial role in fluid and dexterous motion of the thumb axis, little is known about the isolated incidence of pathology at this joint. Etiologies include primary, posttraumatic, and inflammatory arthritis. For early, isolated degenerative disease, arthroscopic synovectomy has been shown to yield satisfactory results. For more advanced disease, fusion is the benchmark. The literature suggests that increased flexion angles may mitigate development of trapeziometacarpal arthritis. In case of advanced arthropathy of the entire thumb axis, arthroplasty is a viable option to reduce pain, preserve motion, and thus limit progression of adjacent joint disease. Special considerations should be given to the rheumatoid thumb because a select combination of treatments for each deformity is thought to best address the unique pathomechanics.

A client-centered approach for thumb carpometacarpal joint osteoarthritis pain: Two case studies

DESIGN

Case study.

INTRODUCTION

Hand therapists are often called upon to provide treatment for thumb carpometacarpal joint osteoarthritis.

PURPOSE

These 2 case studies present a client-centered approach in the selection of orthoses and joint protection strategies for patients with thumb carpometacarpal joint osteoarthritis. At baseline, the participants presented with pain, decreased active range of motion, decreased pinch strength, and limitations in activity and participation.

METHODS

The outcome measures utilized at study entry and 6 weeks included the pain Visual Analog Scale, the Australian Canadian Osteoarthritis Hand Index, the Disabilities of the Arm, Shoulder and Hand questionnaire, the Canadian Occupational Performance Measure, active range of motion measured with goniometry, and pinch strength measured with a pinch gauge. The Canadian Occupational Performance Measure facilitated the client-centered approach by identifying occupational performance issues and rating the participant's performance and satisfaction for each. Each participant was prescribed a different orthotic design, received client-centered joint protection instruction, and evidence-based exercises.

RESULTS

After 6 weeks, both clients had decreased pain and improvement in their activities, participation, and satisfaction.

DISCUSSION

Using a client-centered approach can help therapists to carefully consider a patient's occupational needs when designing and fabricating orthoses and customizing their joint protection education for carpometacarpal joint osteoarthritis.

CONCLUSION

Focusing rehabilitation strategies on that which is most important to the client should be considered to optimize their occupational performance.

Diamond Stress View Radiograph for Thumb Metacarpophalangeal Hyperextension

BACKGROUND

Successful surgical management of thumb carpometacarpal (CMC) arthritis requires treatment of coexisting metacarpophalangeal (MCP) hyperextension deformity when present. The surgeon's decision to offer thumb CMC arthritis patients the option of no additional treatment, MCP capsulodesis, or MCP arthrodesis relies on the severity of the MCP deformity measured in clinic. The authors present a novel patient-performed radiographic stress view to measure MCP hyperextension.

METHODS

Fifty-seven thumbs in 30 consecutive patients offered thumb CMC arthroplasty were enrolled. Clinic goniometer measurements, patient-performed stress view radiographs, and intraoperative manual stress views of each MCP joint were documented for study. Paired samples t test was used to compare the differences between the preoperative measurements and intraoperative measurements of the right and left thumb groups.

RESULTS

The clinic goniometer measurements were significantly different ( P = .0001) than the MCP stress view obtained while the patient was under anesthesia. The difference in the new patient-derived x-ray stress view was not statistically significant compared with the stress view under anesthesia in the left ( P = .91) or right ( P = .53) groups.

CONCLUSIONS

This new patient-performed stress view of the MCP joint allows accurate, objective measurement of hyperextension to aide in the decision making and patient education for the need of additional MCP joint surgery when addressing thumb CMC arthritis.

A novel experimental design for the measurement of metacarpal bone loading and deformation and fingertip force

Background

Musculoskeletal and finite element modelling are often used to predict joint loading and bone strength within the human hand, but there is a lack of in vitro evidence of the force and strain experienced by hand bones.

Methods

This study presents a novel experimental setup that allows the positioning of a cadaveric digit in a variety of postures with the measurement of force and strain experienced by the third metacarpal. The setup allows for the measurement of fingertip force as well. We tested this experimental setup using three cadaveric human third digits in which the flexor tendons were loaded in two tendon pathways: (1) parallel to the metacarpal bone shaft, with bowstringing; (2) a semi-physiological condition in which the tendons were positioned closer to the bone shaft.

Results

There is substantial variation in metacarpal net force, metacarpal strain and fingertip force between the two tendon pathways. The net force acting on the metacarpal bone is oriented palmarly in the parallel tendon condition, causing tension along the dorsum of the metacarpal shaft, while the force increases and is oriented dorsally in the semi-physiological condition, causing compression of the dorsal metacarpal shaft. Fingertip force is also greater in the semi-physiological condition, implying a more efficient grip function. Inter-individual variation is observed in the radioulnar orientation of the force experienced by the metacarpal bone, the fingertip force, and the strain patterns on the metacarpal shaft.

Conclusion

This study demonstrates a new method for measuring force and strain experienced by the metacarpal, and fingertip force in cadaveric digits that can, in turn, inform computation models. Inter-individual variation in loads experienced by the third digit suggest that there are differences in joint contact and/or internal bone structure across individuals that are important to consider in clinical and evolutionary contexts.

In vivo biomechanical behavior of the trapeziometacarpal joint in healthy and osteoarthritic subjects

BACKGROUND

The contact biomechanics of the trapeziometacarpal joint have been investigated in several studies. However, these led to conflicting results and were mostly performed in vitro. The purpose of this study was to provide further insight on the contact biomechanics of the trapeziometacarpal joint by in vivo assessment of healthy and osteoarthritic subjects.

METHODS

The hands of 16 healthy women and 6 women with trapeziometacarpal osteoarthritis were scanned in positions of maximal thumb extension, flexion, abduction and adduction during three isometric tasks (lateral key pinch, power grasp and jar twist) and in thumb rest posture (relaxed neutral). Three-dimensional surface models of the trapezium and first metacarpal were created for each thumb configuration. The articular surface of each bone was measured in the neutral posture. A computed tomography-based proximity mapping algorithm was developed to calculate the distance between opposing joint surfaces, which was used as a surrogate for intra-articular stress.

FINDINGS

Distinct proximity patterns were observed across tasks with a recurrent pattern reported on the volar aspect of the first metacarpal. The comparison between healthy and arthritic subjects showed a significantly larger articular area, in parallel with a significant joint space narrowing and an increase in proximity area in arthritic subjects. We also observed severe articular deformations in subjects with late stage osteoarthritis.

INTERPRETATION

This study has increased our insight in the contact biomechanics of the trapeziometacarpal joint during tasks and positions of daily life in healthy and arthritic subjects, which might contribute to a better understanding of the occurrence mechanisms of degenerative diseases such as osteoarthritis.

Kinematic Analyses of the Thumb during Simulated Posteroanterior Glide Mobilization

Objective

Thumb problems are common in some health professionals such as physical therapists. The purpose of this case-control study is to investigate the influence of clinical experience and different mobilization techniques on the kinematics of the thumb.

Methods

Twenty-three participants without exposure to manual techniques (the Novice Group) and fifteen physical therapists with at least 3 years of orthopedic experience (the Experienced Group) participated. The kinematics of the thumb while performing 3 different simulated posteroanterior (PA) glide mobilization techniques on a load cell was monitored. These 3 techniques were: 1) unsupported, 2) with digital support and 3) with thumb interphalangeal joint supported by the index finger. The amount of forces exerted were 25% to 100% of maximum effort at 25% increments. The main effects of experience and technique on thumb kinematics were assessed.

Results

Both experience and technique had main effects on the flexion/extension angles of the thumb joints. Experienced participants assumed a more flexed position at the carpometacarpal (CMC) joint, and the novice participants performed with angles closer to the neutral position (F = 7.593, p = 0.010). Participants’ metacarpophalangeal (MCP) joints were in a more flexed position while performing PA glide with thumb interphalangeal (IP) joint supported by the index as compared to the other two techniques (p < .001).

Conclusions

Negative correlations were generally obtained between the sagittal plane angles of adjacent thumb joints during mobilization/manipulation. Therapists are recommended to treat patient with more stable PA glide mobilization techniques, such as PA glide with thumb interphalangeal joint supported by the index finger, to prevent potential mobilization-related thumb disorders.

In vivo contact biomechanics in the trapeziometacarpal joint using finite deformation biphasic theory and mathematical modelling

The assessment of the contact biomechanics in the trapeziometacarpal (TMC) joint during functional tasks represents a relevant way to obtain a better understanding of the onset of osteoarthritis (OA). CT scans of the hand region of 20 female volunteers were taken in relaxed neutral, lateral key pinch and power grasp configuration. 3D models of the first metacarpal (MC1) and the trapezium were created. The articular area of each bone was quantified and a mathematical model was developed in Matlab to evaluate the projected contact area and stress distribution of each bone. The articular areas of the MC1 and the trapezium presented no significant difference. A slightly smaller projected contact area was calculated for the trapezium compared to the MC1. Similar amounts of stress were reported in the neutral and lateral pinch configurations. The highest stress levels were observed during power grasp. Very consistent results for high stress location on the volar/radial articular sub-region were found in the neutral and power grasp configurations. More variation was reported during lateral pinch. The mathematical model presented in this paper offers the possibility to predict contact patterns within the TMC joint based on in vivo CT images.

Sesamoid bone transfer for metacarpophalangeal hyperextension instability of the thumb: A CT-osteoabsorptiometry study

BACKGROUND AND AIM

Hyperextension instability of the metacarpophalangeal (MCP) joint of the thumb may result in pain, malfunction, and accelerated osteoarthritis in the carpometacarpal (CMC) joint. One method of treatment is sesamoid arthrodesis. The aim of this study is to investigate if a sesamoid transfer as a treatment of hyperextension instability of the thumb MCP joint leads to an altered distribution of the subchondral mineralisation and a negative clinical outcome.

METHODS

Sesamoid transfer was performed on 12 patients with hyperextension instability of the MCP joint of the thumb. The range of motion (ROM) and radiologic outcome were assessed. Pinch and power grip strength were measured and compared to the nonoperated side. To determine the areas of maximum subchondral mineralisation in the joint, computed tomography (CT)-osteoabsorptiometry was performed to determine the long-term stress distribution within the joint.

RESULTS

The distributions of the stress zones in the operated and nonoperated thumbs were not statistically different a median of 5 years following the sesamoid transfer procedure. There was no difference in the functional and radiological results between the operated and nonoperated thumbs.

CONCLUSION

If it is assumed that the nonoperated thumb represents the normal condition for each individual, then it may be deduced that the operation achieves good clinical results, and the distribution of the subchondral mineralisation does not change.

Effect of prior experience and task stability on the intrinsic muscle activity of the thumb

Manual techniques involving the use of the thumb are commonly employed by physical therapists for treating patients with vertebral disorders. The demands on the intrinsic muscles of the thumb in these manual tasks are very different from those of the pinch tasks. The aim of this study was to investigate the influence of clinical experience and different mobilization techniques on the electromyographic activity (EMG) of thumb intrinsic muscles. Fifteen participants without exposure to manual techniques (the Novice Group) and fifteen physical therapists with at least 3 years of orthopaedic experience (the Experienced Group) participated. Each participant exerted thumb tip forces with 3 different posterioanterior (PA) glide techniques including unsupported, with digital support and with thumb interphalangeal joint supported by the index finger. The exerted force was increased from 25% to 100% maximum force at 25% increments on a 6 component load cell. The thumb tip force and EMG activity of four intrinsic muscles (flexor pollicis brevis, adductor pollicis, abductor pollicis brevis, first dorsal interosseus) were recorded with surface electrodes. Both experience and technique influenced intrinsic muscle activity of the thumb. While participants of both groups generated the same magnitude of force, experienced participants generated less intrinsic muscle activity while performing PA glide through practice. However, novice participants increased activity of the intrinsic muscles in accordance with the stability status of the technique. PA glide with thumb interphalangeal joint supported by the index finger was a more stable technique as evidenced by smallest relative errors of thumb tip force.

Increased range of motion and decreased strength of the thumb in massage practitioners with thumb pain

The purpose of this study was to compare the range of motion (ROM) and strength of the metacarpophalangeal (MP) and interphalangeal (IP) joints among massage practitioners with and without thumb pain and control subjects. Sixteen massage practitioners with thumb pain, 16 practitioners without thumb pain, and 16 control subjects participated in this study. ROM of flexion, extension, and abduction in the MP joint; ROM of flexion and extension in the IP joint of the thumb; strength of the flexor pollicis brevis (FPB), extensor pollicis brevis (EPB), abductor pollicis brevis, flexor pollicis longus (FPL), and extensor pollicis longus measured in all subjects. ROM of extension and abduction in the MP joint were significantly increased in massage practitioners with and without thumb pain compared with control subjects. ROM of extension in the IP joint was significantly increased in massage practitioners with thumb pain compared with those without thumb pain. The strength of the EPB and FPL muscle was significantly decreased in massage practitioners with thumb pain compared with those without thumb pain and control subjects, respectively. In addition, there was significantly increased EPB/FPB strength in massage practitioners without thumb pain compared to those with thumb pain and control subjects.

[Injuries and posttraumatic osteoarthritis of the first carpometacarpal joint]

BACKGROUND

Precise function of the hand is crucially characterized by opposition movement of the thumb, only possible because of the functional anatomy of the first carpometacarpal joint. High functional demands to this joint consequently lead to the highest rate of osteoarthritis of the hand joints and loss of function. Carpometacarpal (CMC) osteoarthritis of the thumb is rarely seen in posttraumatic cases. It can be caused by fractures involving the joint surfaces of both, the trapezium or the first metacarpal, whereas dislocations of the carpometacarpal joint itself only occasionally lead to osteoarthritis.

OBJECTIVES

Identification and compilation of current concepts in diagnosis and therapy of posttraumatic carpometacarpal osteoarthritis of the thumb.

METHODS

Selective PubMed and Cochrane review, data obtained from own patient investigations and author's experiences were used.

RESULTS

Adequate treatment of the injury will minimize the risk for future malfunction. In early stages, arthroscopy is a valuable method for the diagnosis and treatment of posttraumatic rhizarthrosis. For all stages, a multitude of operative procedures are described and being used but yet not finally assessed for effectiveness. Advanced osteoarthritis of the first CMC joint is widely treated by trapeziectomy, which is suitable for most patients, and considered as gold standard. Additional procedures like suspension, interposition or k-wire transfixation do not provide any significant advantage and lead to comparable results. It is advisable to treat hyperextension of the metacarpophalangeal joint of the thumb at any stage of CMC osteoarthritis.

In vivo analysis of trapeziometacarpal joint kinematics during pinch tasks

This study investigated how the posture of the thumb while performing common pinch movements and the levels of pinch force applied by the thumb affect the arthrokinematics of the trapeziometacarpal joint in vivo. Fifteen subjects performed the pinch tasks at the distal phalange (DP), proximal interphalangeal (PIP) joint, and metacarpophalangeal (MP) joint of the index finger with 0%, 50%, and 80% of maximal pinch forces by a single-axis load cell. 3D images of the thumb were obtained using the computed tomography. The results show that the reference points moved from the central region to the dorsal-radial region when changing from pinching the DP to the MP joint without pinching force being applied. Pinching with 80% of the maximum pinching force resulted in reference points being the closest to the volar-ulnar direction. Significant differences were seen between 0% and 50% of maximum pinch force, as well as between 0% and 80%, when pinching the MP joint in the distal-proximal direction. The effects of posture of the thumb and applied pinch force on the arthrokinematics of the joint were investigated with a 3D model of the trapeziometacarpal joint. Pinching with more than 50% of maximum pinch force might subject this joint to extreme displacement.

Preference of lid design characteristics by older adults with limited hand function

INTRODUCTION

Although opening jars is problematic for older adults, little is known about the best interface design for jar lids.

PURPOSE OF THE STUDY

To evaluate preferences in current and new lids for persons self-reporting difficulty with opening jars.

METHODS

Participants were twenty-six older females with hand pain. Preference ratings were obtained for twenty-four current and forty-two new lid designs of different sizes, shapes, and textures.

RESULTS

Current lids with taller heights, larger diameters, and textured sides were preferred. Texture compensated for limitations of shorter and smaller diameter lids. Preferred characteristics in new smaller diameter lids included taller height, non-circular top shapes, and concave side shapes. Taller height, regardless of shape, was preferred for new medium diameter lids. Least preferred for small and medium lids was the short height, traditional circular shape.

CONCLUSIONS

The preferences of jar lids made by elderly females with hand pain support the recommendations commonly suggested by clinicians to increase the height, diameter, texture, and shape of jars, especially for lids smaller than 40 mm.

Effects of a dynamic stability approach in conservative intervention of the carpometacarpal joint of the thumb: a retrospective study

STUDY DESIGN

Retrospective cohort.

INTRODUCTION

Conservative intervention of carpometacarpal joint (CMC) thumb pain, caused by osteoarthritis and ligament laxity, is frequently seen in hand therapy. Traditional intervention for pain and disability reduction includes orthoses, exercises, and joint protection education. The literature on conservative management is unclear which design or program of exercises create an effective result. Results of a conservative dynamic stability interventional model for thumb pain are presented as a design which positively effects pain and disability.

PURPOSE OF THE STUDY

The purposes were to primarily investigate change in pain and disability in persons with CMC pain in a dynamic stability modeled approach to intervention, and secondarily, to assess the average number of visits and the duration of total visits in this model.

METHODS

A retrospective chart review was completed on 35 charts of those seen at a multicenter hand therapy clinic. The pain and disability scores from the QuickDASH were used as outcome measures.

RESULTS

The average group pain and disability scores improved by 17.9% (p < .01) and 19.3% (p < .01) respectively, with average individual disability improvement of 15.7%, which is greater than the accepted MCID. The average patient visits were 2.37 over an average range of 44.5 days. The group demographics match current literature: 31 females to 4 males, with average age of 58 years (range of 30-82 years).

CONCLUSION

Significant reduction in pain and disability is noted with a conservative dynamic stability modeled approach to intervention, with information on average visits and duration in this model of care for individuals with thumb pain at the CMC joint.

LEVEL OF EVIDENCE

4.

An exercise program for carpometacarpal osteoarthritis based on biomechanical principles

A review of the literature was performed to design a hand exercise regimen based on biomechanical principles of the carpometacarpal (CMC) joint and the forces that act upon the joint. Sixteen biomechanical studies were included in the review: four studies developed a mathematical model of the thumb and 12 performed cadaveric dissections to study the CMC joint. Clinical application of the biomechanical findings from the studies was synthesized into specific recommendations for a hand exercise program to preserve CMC joint range of motion and increase the strength of the stabilizing muscles of the thumb. The exercise regimen was developed in accordance with recommendations of the American College of Sports Medicine guidelines for the development of individualized exercise prescriptions.

LEVEL OF EVIDENCE

4.

Functional patterns of thumb key pinch and their influence on thumb strength and stability

Introduction

Trapeziometacarpal osteoarthritis (TMC OA) is a common condition frequently related to instability and hypermobility. Many factors are involved in the development of this degenerative process. Recent research suggests that the position of the metacarpophalangeal (MCP) joint may influence TMC joint contact wear patterns and subsequent development of OA. The aim of this study is to explore the alignment of the MCP joint of the thumb during lateral pinch in order to describe the naturally occurring alignment in a group of healthy volunteers without symptoms.

Methods

One hundred and nine participants were asked to apply a lateral pinch manoeuvre to a pinchmeter, while their thumbs were assessed. Passive hypermobility of the thumb MCP (MCP) joint was assessed, key pinch strength was measured, key pinch position was photographed and the angle of the joints during the assessment was measured.

Results

Four different functional pinch patterns were identified. The most frequent pattern seems to be MCP hyperextension described by Moulton as harmful for the TMC joint. The level of strength obtained did not correspond to the pinch pattern used, and hypermobility of the thumb MCP joint did not determine the position of the thumb during key pinch.

Conclusion

Four different thumb postures were identified during lateral pinch; however, these postures were not associated with any difference in pinch strength. We conclude that the more unstable and mechanically inefficient postures are compensated by functional capacity.

Effects of taping on thumb alignment and force application during PA mobilisations

Work related thumb pain (WRTP) is a major problem among manipulative physiotherapists. Therapists who maintain the thumb joints in an extended alignment during PA mobilisation experience less WRTP. The purposes of this study were to investigate what effect taping of the thumbs has on thumb alignment during mobilisation and to gain normative data on the mobilisation forces applied by student physiotherapists. Forty final year student physiotherapists participated and were asked to apply a grade III PA mobilisation onto the C7 vertebra of one of 32 asymptomatic models. Participants were then instructed to apply the same mobilisation onto a force measurement instrument, in both the tape and no tape conditions, while the alignment of their metacarpophalangeal (MCP) and interphalangeal (IP) joints was noted via video recorder. Thumb alignment improved in 72.5% of participants post taping, with significant increases in the number of MCP joints maintained in a neutral alignment (p < 0.05). The mean peak mobilisation force applied by the students was 70.9 N. Taping of the thumbs prior to PA mobilisation improved thumb alignment during mobilisation in this cohort of undergraduate students, thus potentially influencing one of the contributory factors to WRTP.

Long-term follow-up of basal joint resection arthroplasty of the thumb with transfer of the abductor pollicis brevis origin to the flexor carpi radialis tendon

PURPOSE

To investigate the long-term functional and clinical outcomes of a tendon transfer during basal joint interposition arthroplasty for osteoarthritis of the basal joint of the thumb, in which the origin of the abductor pollicis brevis (APB) and opponens pollicis is transferred to the flexor carpi radialis tendon, in order to increase the abduction moment arm of the thumb and provide dynamic stabilization of the base of the first metacarpal.

METHODS

We observed 22 patients, who received basal joint interposition arthroplasty with APB and opponens pollicis tendon transfer, over an average of 9 years (range, 3-20 years). Subjective outcome measures included patient satisfaction scores, visual analog scale scores for pain, and Disabilities of the Arm, Shoulder and Hand (DASH) scores. Clinical evaluations included thumb range of motion, grip strength, and pinch strength.

RESULTS

At an average follow-up of 9 years, 95% of patients (21 out of 22) subjectively scored the procedure as good or excellent and reported improvement in activities of daily living. Mean visual analog scale pain score was 4.4 at rest and 7.8 with activity (out of 100), and mean DASH score was 13.3 (out of 100). Average grip strength of the operated hand was equal to that of the contralateral hand, and lateral and tip pinch strengths were 79% and 93%, respectively, of the contralateral hand. No intraoperative or early postoperative complications were reported, although 1 patient whose procedure was performed as treatment for failed silastic arthroplasty reported metacarpal instability at 9-year follow-up (DASH score of 22).

CONCLUSIONS

Basal joint arthroplasty with APB and opponens pollicis tendon transfers provides excellent long-term results for carpometacarpal thumb osteoarthritis. The procedure is safe, with a low complication rate. Its success has long-term durability as measured by patient satisfaction, functional outcome measures, range of motion, and strength.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Effect of general flexibility on thumb-tip force generation - implication for mobilization and manipulation

Pain involving basal joints of the thumb is one of the major occupation-related disorders for orthopedic physiotherapists and manual therapists. The thumb-tip force generation while performing manual techniques may be influenced not only by the specific manual techniques employed but also by general flexibility of the therapist. The purpose of this study was to investigate the influence of general flexibility and different techniques on thumb-tip force generation. Twenty-three subjects with no exposure to manual techniques and 15 physical therapy clinicians with at least 3 years of orthopedic experience participated. The general flexibility of each subject was assessed by Beighton score (BS). Each subject was requested to exert a maximal force on a six-component load cell with the thumb unsupported (T1), with the rest of digits supported (T2), and with interphalangeal joint of the thumb supported by the index (T3).The thumb-tip force was normalized by body weight. The thumb-tip force generation is influenced not only by the differences in technique employed by the therapists, but also by the general flexibility of the therapists. Physiotherapists with excessive thumb flexibility are advised to perform PA glide with IP joint supported to protect the thumb joints from injury.

Treatment of advanced carpometacarpal joint disease: carpometacarpal arthroplasty with ligament interposition

Basal joint arthritis is a common condition, primarily affecting postmenopausal women. Persistent pain and functional impairment despite conservative treatment are indications for operative intervention. Ligament reconstruction and tendon interposition (LRTI) arthroplasty is one of the most popular and time-tested operations to treat metacarpal instability and basal joint arthritis. LRTI incorporates three fundamental principles that address the underlying anatomic pathology: (1) trapezium excision, either partial or complete, to eliminate eburnated bone and the source of pain; (2) anterior oblique ligament reconstruction for carpometacarpal joint stability; and (3) tendon interposition to minimize axial shortening and prevent bony impingement.

Early treatment of degenerative arthritis of the thumb carpometacarpal joint

Degenerative arthritis of the thumb carpometacarpal (CMC) joint is a common disorder that may affect anyone but most frequently affects the postmenopausal female population. Because of its high prevalence, the management of the condition has been a popular topic among hand surgeons and therapists worldwide. There are many decisions to consider when devising the appropriate treatment plan for each patient. In particular, early stages of thumb CMC joint arthritis may be treated nonoperatively or with less invasive surgical techniques to relieve symptoms, restore function and strength, stop the progression of the disease, and even potentially reverse the process. This article explores treatment options at the disposal of primary care physicians and hand surgeons for early thumb CMC arthritis.

Physical diagnosis and radiographic examination of the thumb

Arthritis of the thumb joints is a common problem and remains a significant cause of morbidity in the adult population. Careful physical examination is critical in the assessment of these patients, given the large differential diagnosis of conditions affecting the thumb and the radial side of the wrist. Because treatment should be specifically directed at the area of pathology, adequate diagnosis is vital. Plain radiograph evaluation remains the diagnostic modality of choice in the evaluation of patients with degenerative conditions about the hand and wrist.

Anatomy and pathomechanics of the thumb

The prehensile thumb provides the human mind an outlet for coordinated activity through its fine motions of prehension, opposition, and circumduction. A comprehensive understanding of the anatomy and biomechanics of the thumb provides a foundation on which functional disorders may be recognized and effectively treated.

Carpometacarpal joint disease: addressing the metacarpophalangeal joint deformity

The successful surgical treatment of arthrosis of the carpometacarpal articulation of the thumb requires a thorough understanding and evaluation of the intercalated axis of the first ray. A hyperextension/adduction deformity commonly occurs at the metacarpophalangeal joint of the thumb with advanced stages of carpometacarpal arthrosis. Failure to recognize and treat the metacarpophalangeal deformity may result in continued pain and poor outcomes. Additionally, the stability of the ligament reconstruction may become compromised, resulting in recurrence of deformity and longitudinal collapse. This article presents an orderly means of clinical and radiographic evaluation of this deformity and recommends surgical treatments to correct hyperextension and maximize functional outcomes. A treatment algorithm is provided.

Microstructural adaptation in trapezial bone due to subluxation of the thumb

Although the thumb saddle is one of the most common sites of degenerative osteoarthritis in the hand, little is known about the altered microstructure in osteoarthritic trapezial bones. External forces resulting from subluxation of the carpometacarpal joint of the thumb (CMC I) should provoke microstructural changes in the trapezium. The purpose of this study was to compare the regional differences of the microstructure between osteoarthritic and healthy trapezial bones. Fifteen trapezia harvested from female patients with radiologically and clinically diagnosed saddle joint osteoarthritis (OA) were compared with 15 unaffected controls. Microstructural parameters, such as bone volume ratio (BV/TV), three-dimensional connectivity (Conn.D), trabecular number (Tb.N), and trabecular thickness (Tb.Th) were studied using a microcomputed tomography (microCT) system. While the trapezial height in OA was 22% less, the sclerotic subchondral bone layer thickness was 50% higher in OA compared with the control group (p < 0.001). In the OA group there was a 42% higher bone volume ratio (p <or= 0.001), an 18% increase in Tb.Th (p = 0.006), and a 10% greater Tb.N (p = 0.034) compared with the control group. Although in both groups BV/TV was significantly lower in the radial region, the radial column showed the highest relative increase in bone volume and structure compared with the control group (+67% BV/TV, +20% Tb.Th, +23% Tb.N). The reinforcement of the bony microstructure in CMC I OA, especially at the radial side, is a sign for bone adaptation reacting to radially shifted joint forces. This has to be considered during the development of new prosthetic alternatives.

The ABJS 2005 Nicolas Andry Award: osteoarthritis and injury at the base of the human thumb: survival of the fittest?

The basal joint complex, consisting of four trapezial articulations providing a foundation for the thumb, defines our anatomic evolution from a Simian ancestry by providing an opposable member. Ironically, the trapeziometacarpal joint also is responsible for the most common malady leading to operative reconstruction in the upper limb for arthritic disease. The paradoxic relationship between these two facts has stimulated investigation that has defined the scientific basis for common surgical procedures and provided a foundation for the development of novel treatments for conditions at the base of the thumb. Patterns of articular surface degeneration are determined by areas of contact loading in the joint. Ligament reconstruction, metacarpophalangeal joint flexion splinting, and extension metacarpal osteotomy for early disease resulting from instability all have biomechanical justification for their clinical application. Likewise, percutaneous pinning of Bennett's fracture dislocation is predicated on reestablishing functional continuity of the beak ligament and unloading the palmar joint surfaces. For advanced disease, ligament reconstruction has become the cornerstone of arthroplasty. Perhaps most importantly, the trapeziometacarpal joint as an instability model can provide insight into the interplay of mechanical and biological factors in producing the primary lesion associated with osteoarthritis.

Kinematic and contact stress analysis of posterior malleolus fractures of the ankle

OBJECTIVE

To determine if there are measurable dynamic contact stress aberrations and kinematic abnormalities (instability) that have not been observed in conventional static loading studies of posterior malleolar ankle fractures.

DESIGN

Cadaveric fracture model.

SETTING

Biomechanics laboratory.

INTERVENTION

Seven fresh cadaveric specimens were fixed in an unconstrained testing apparatus and loaded to one body weight. The ankle was moved from 25 degrees of plantarflexion to 15 degrees of dorsiflexion. The model included the intact ankle and four fracture simulations (50% fracture without internal fixation, 2 mm gap and step malreductions, and anatomically fixed).

MAIN OUTCOME MEASURE

Motion at the ankle was monitored with an electromagnetic tracking device, and intra-articular contact stresses were measured using a real-time stress sensor.

RESULTS

There were no kinematic abnormalities suggestive of tibiotalar subluxation in any of the fracture simulations. There was no increase in peak contact stress in any of the fracture models compared with the unfractured model. However, there was a shift in the location of the contact stresses to a more anterior and medial location following the fracture. When summed over the range of motion, these areas of cartilage bore significantly higher cumulative contact stresses relative to the nonfracture situation.

CONCLUSIONS

We found no talar subluxation and no increase in contact stresses near the articular incongruity, making it unlikely that these factors explain the increased incidence of arthrosis after trimalleolar fractures (OTA/AO classification 44 B3 fractures). Rather, we found that the joint remaining bears increased stress and that the center of stress shifts anteriorly, loading cartilage that normally sees little load.